Development of explosive compositions for military applications has historically been motivated by the need for explosives with high energy output. The need for increased explosive performance of such high energy munitions has become ever more important in modern military programs. Increasing the energy output of energetic compositions, however, couples with an increased problem of risk of unwanted detonation due to shock or friction. This problem has always plagued the military, but in recent years it has become more critical. As explosive power increases, the materials tend to become more sensitive and vulnerable to accidental detonation.
Historical production of high energy materials with suitable handling properties and low risk of unwanted detonation has typically followed a few common pathways. The first is to combine a high energy material with a lower energetic binder such as trinitrotoluene or nitrocellulose. Such compositions reduce the amount of high energy material, but remain too unstable for modern use. A second path is to increase the amount of high energy material, but combine it with an inert binder such as an organic wax or polymer. The problem becomes finding the right balance of high energy material and inert binder to provide the necessary balance of explosive power and safety. The final approach taken is to synthesize new high energy compositions that may inherently possess the right balance of explosive power and insensitivity to unwanted detonation.
Further adding complexity to methods to craft an explosive with the proper power and safety, is the fact that there are different types of packaging or uses that dictate physical characteristics of the material either during production or use. Castable explosives, as one type, are classified either as melt-cast or as plastic bonded. Melt-cast systems require the melting of the explosive, for example TNT (m.p. 81° C.), and casting into a munition. Plastic bonded systems involve a mixture of one or more explosives with a polymeric binder, casting into a munition or mold, and curing of the binder. Thus, any compositions for improving safety or handling properties of the energetic material must have the physical characteristics that allow them to function in either a melt-castable system or a plastic bonded system as desired.
The explosive formulations developed to date using the techniques described above have not yielded high energy output explosives that demonstrate a low enough susceptibility to sympathetic detonation to be considered for use in insensitive munitions. Previous efforts have failed in this respect in that they did not discover the proper combination filler or binder (i.e. in either chemical type or concentration level) to yield these properties.
As such, there is a need for new explosive compositions with enhanced detonation properties and improved safety.